Abstract

Optical properties of Nuclepore filter media, as used in the integrating plate (IP) method for determination of aerosol light absorption, have been examined. It has been shown that the internal reflectance is high for the Nuclepore filters typically used and that changes in this value result in spurious contributions to absorption measurements. It has been found that aerosol particles on the filter surface can substantially alter the internal reflection coefficient of this material for a wide variety of aerosol types. The amount and nature of this change are found to vary with optical and physical properties of the aerosol in contact with the filter surface. A simple mathematical model of the optical system is described that allows for variations in Nuclepore internal reflectance. Implications of this model and data suggest that light absorption measurements as determined via the IP method may be systematically overestimated for certain samples by as much as 30%. Estimates of the magnitude of this inaccuracy for a given IP absorption measurement are presented based on the model and supplementary back reflectance measurements.

© 1982 Optical Society of America

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References

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  1. R. J. Charlson, M. J. Pilat, J. Appl. Meteorol. 8, 1001 (1969).
    [CrossRef]
  2. J. H. Joseph, W. J. Wiscombe, J. Atmos. Sci. 33, 2352 (1976).
    [CrossRef]
  3. J. B. Pollack, O. B. Toon, Geophys. Res. Lett. 8, 26 (1981).
    [CrossRef]
  4. J. D. Lindberg, L. S. Laude, Appl. Opt. 13, 1923 (1974).
    [CrossRef] [PubMed]
  5. K. Fischer, Beitz. Phys. Atmos. 43, 224 (1970). Beiträge zur Physik der Atmosphare, 43, Band, 1970, 5, 244–254.
  6. Z. Yasa, N. M. Amer, H. Rosen, A. D. A. Hasen, T. Novakov, Appl. Opt. 18, 2528 (1979).
    [CrossRef] [PubMed]
  7. E. M. Patterson, G. W. Grams, Atmos. Tech. 12, (1980).
  8. C. I. Lin, Ph.D. Dissertation, U. Washington, Seattle (1973).
  9. C.-I. Lin, M. B. Baker, R. J. Charlson, Appl. Opt. 12, 1356 (1973).
    [CrossRef] [PubMed]
  10. R. E. Weiss, Ph.D. Dissertation, U. Washington, Seattle (1980).
  11. R. E. Weiss, A. P. Waggoner, R. J. Charlson, “Studies of the Optical, Physical, and Chemical Properties of Light Absorbing Aerosols,” in Proceedings, Conference on Carbonaceous Particles in the Atmosphere (Lawrence Berkeley Laboratory, Berkeley, Calif., LBL-9037, 1978).
  12. A. D. Clarke, A. P. Waggoner, Appl. Opt. 21, 398 (1982).
    [CrossRef] [PubMed]
  13. R. E. Weiss, A. P. Waggoner, in GM International Symposium on Particulate Carbon: Atmospheric Life Cycles (General Motors, Warren, Mich., 1980).
  14. J. L. Michaelson, in American Institute of Physics Handbook, D. E. Gray, Ed. (McGraw-Hill, New York, 1972), p. 6–162.
  15. S. E. Orchard, J. Opt. Soc. Am. 59, 12 (1969).
    [CrossRef]
  16. G. Kortum, Reflectance Spectroscopy (Springer, Berlin, 1969), p. 13.
  17. M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
    [CrossRef]
  18. A. P. Waggoner, R. E. Weiss, Atmos. Environ. 14, 623 (1980).
    [CrossRef]
  19. K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
    [CrossRef]

1982 (1)

1981 (1)

J. B. Pollack, O. B. Toon, Geophys. Res. Lett. 8, 26 (1981).
[CrossRef]

1980 (2)

E. M. Patterson, G. W. Grams, Atmos. Tech. 12, (1980).

A. P. Waggoner, R. E. Weiss, Atmos. Environ. 14, 623 (1980).
[CrossRef]

1979 (1)

1976 (1)

J. H. Joseph, W. J. Wiscombe, J. Atmos. Sci. 33, 2352 (1976).
[CrossRef]

1974 (1)

1973 (1)

1970 (1)

K. Fischer, Beitz. Phys. Atmos. 43, 224 (1970). Beiträge zur Physik der Atmosphare, 43, Band, 1970, 5, 244–254.

1969 (3)

R. J. Charlson, M. J. Pilat, J. Appl. Meteorol. 8, 1001 (1969).
[CrossRef]

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

S. E. Orchard, J. Opt. Soc. Am. 59, 12 (1969).
[CrossRef]

1958 (1)

M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
[CrossRef]

Amer, N. M.

Baker, M. B.

Charlson, R. J.

C.-I. Lin, M. B. Baker, R. J. Charlson, Appl. Opt. 12, 1356 (1973).
[CrossRef] [PubMed]

R. J. Charlson, M. J. Pilat, J. Appl. Meteorol. 8, 1001 (1969).
[CrossRef]

R. E. Weiss, A. P. Waggoner, R. J. Charlson, “Studies of the Optical, Physical, and Chemical Properties of Light Absorbing Aerosols,” in Proceedings, Conference on Carbonaceous Particles in the Atmosphere (Lawrence Berkeley Laboratory, Berkeley, Calif., LBL-9037, 1978).

Clarke, A. D.

Fischer, K.

K. Fischer, Beitz. Phys. Atmos. 43, 224 (1970). Beiträge zur Physik der Atmosphare, 43, Band, 1970, 5, 244–254.

Frank, E. R.

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

Furguson, M. B.

M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
[CrossRef]

Grams, G. W.

E. M. Patterson, G. W. Grams, Atmos. Tech. 12, (1980).

Hasen, A. D. A.

Joseph, J. H.

J. H. Joseph, W. J. Wiscombe, J. Atmos. Sci. 33, 2352 (1976).
[CrossRef]

Katz, M.

M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
[CrossRef]

Kortum, G.

G. Kortum, Reflectance Spectroscopy (Springer, Berlin, 1969), p. 13.

Laude, L. S.

Lin, C. I.

C. I. Lin, Ph.D. Dissertation, U. Washington, Seattle (1973).

Lin, C.-I.

Lindberg, J. D.

Lodge, J. P.

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

Michaelson, J. L.

J. L. Michaelson, in American Institute of Physics Handbook, D. E. Gray, Ed. (McGraw-Hill, New York, 1972), p. 6–162.

Novakov, T.

Orchard, S. E.

S. E. Orchard, J. Opt. Soc. Am. 59, 12 (1969).
[CrossRef]

Patterson, E. M.

E. M. Patterson, G. W. Grams, Atmos. Tech. 12, (1980).

Pilat, M. J.

R. J. Charlson, M. J. Pilat, J. Appl. Meteorol. 8, 1001 (1969).
[CrossRef]

Pollack, J. B.

J. B. Pollack, O. B. Toon, Geophys. Res. Lett. 8, 26 (1981).
[CrossRef]

Rosen, H.

Sanderson, H. P.

M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
[CrossRef]

Sheesley, D. C.

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

Spurny, K. R.

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

Toon, O. B.

J. B. Pollack, O. B. Toon, Geophys. Res. Lett. 8, 26 (1981).
[CrossRef]

Waggoner, A. P.

A. D. Clarke, A. P. Waggoner, Appl. Opt. 21, 398 (1982).
[CrossRef] [PubMed]

A. P. Waggoner, R. E. Weiss, Atmos. Environ. 14, 623 (1980).
[CrossRef]

R. E. Weiss, A. P. Waggoner, in GM International Symposium on Particulate Carbon: Atmospheric Life Cycles (General Motors, Warren, Mich., 1980).

R. E. Weiss, A. P. Waggoner, R. J. Charlson, “Studies of the Optical, Physical, and Chemical Properties of Light Absorbing Aerosols,” in Proceedings, Conference on Carbonaceous Particles in the Atmosphere (Lawrence Berkeley Laboratory, Berkeley, Calif., LBL-9037, 1978).

Weiss, R. E.

A. P. Waggoner, R. E. Weiss, Atmos. Environ. 14, 623 (1980).
[CrossRef]

R. E. Weiss, Ph.D. Dissertation, U. Washington, Seattle (1980).

R. E. Weiss, A. P. Waggoner, R. J. Charlson, “Studies of the Optical, Physical, and Chemical Properties of Light Absorbing Aerosols,” in Proceedings, Conference on Carbonaceous Particles in the Atmosphere (Lawrence Berkeley Laboratory, Berkeley, Calif., LBL-9037, 1978).

R. E. Weiss, A. P. Waggoner, in GM International Symposium on Particulate Carbon: Atmospheric Life Cycles (General Motors, Warren, Mich., 1980).

Wiscombe, W. J.

J. H. Joseph, W. J. Wiscombe, J. Atmos. Sci. 33, 2352 (1976).
[CrossRef]

Yasa, Z.

Anal. Chem. (1)

M. Katz, H. P. Sanderson, M. B. Furguson, Anal. Chem. 30, 1172 (1958).
[CrossRef]

Appl. Opt. (4)

Atmos. Environ. (1)

A. P. Waggoner, R. E. Weiss, Atmos. Environ. 14, 623 (1980).
[CrossRef]

Atmos. Tech. (1)

E. M. Patterson, G. W. Grams, Atmos. Tech. 12, (1980).

Beitz. Phys. Atmos. (1)

K. Fischer, Beitz. Phys. Atmos. 43, 224 (1970). Beiträge zur Physik der Atmosphare, 43, Band, 1970, 5, 244–254.

Environ. Sci. Technol. (1)

K. R. Spurny, J. P. Lodge, E. R. Frank, D. C. Sheesley, Environ. Sci. Technol. 3, 453 (1969).
[CrossRef]

Geophys. Res. Lett. (1)

J. B. Pollack, O. B. Toon, Geophys. Res. Lett. 8, 26 (1981).
[CrossRef]

J. Appl. Meteorol. (1)

R. J. Charlson, M. J. Pilat, J. Appl. Meteorol. 8, 1001 (1969).
[CrossRef]

J. Atmos. Sci. (1)

J. H. Joseph, W. J. Wiscombe, J. Atmos. Sci. 33, 2352 (1976).
[CrossRef]

J. Opt. Soc. Am. (1)

S. E. Orchard, J. Opt. Soc. Am. 59, 12 (1969).
[CrossRef]

Other (6)

G. Kortum, Reflectance Spectroscopy (Springer, Berlin, 1969), p. 13.

C. I. Lin, Ph.D. Dissertation, U. Washington, Seattle (1973).

R. E. Weiss, A. P. Waggoner, in GM International Symposium on Particulate Carbon: Atmospheric Life Cycles (General Motors, Warren, Mich., 1980).

J. L. Michaelson, in American Institute of Physics Handbook, D. E. Gray, Ed. (McGraw-Hill, New York, 1972), p. 6–162.

R. E. Weiss, Ph.D. Dissertation, U. Washington, Seattle (1980).

R. E. Weiss, A. P. Waggoner, R. J. Charlson, “Studies of the Optical, Physical, and Chemical Properties of Light Absorbing Aerosols,” in Proceedings, Conference on Carbonaceous Particles in the Atmosphere (Lawrence Berkeley Laboratory, Berkeley, Calif., LBL-9037, 1978).

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Figures (11)

Fig. 1
Fig. 1

Figurative arrangement for IP method showing incident diffuse light from below: opal glass with surface reflectivity Rs; Nuclepore with external R1 and internal (R2,R3) reflective surfaces; particles and light detection system. (The gap between Nuclepore and opal glass is shown for clarity only.)

Fig. 2
Fig. 2

Ratio of fractional light attenuation (ΔI/I0) over neutral density filter to same measured over opal glass plotted as a function of ΔI/I0 measured over opal glass.

Fig. 3
Fig. 3

Reflectometer: L, tungsten light source (type DZP); S, diffuse reflecting plate; O, opal glass diffuser; N, Nuclepore filter; H, Wood’s Horn (light trap); T, collimating light tube; F, (550-nm) filter; D, detector (VACTEC photodiode VTB 1113B); A, air-cooling holes. (All interior surfaces above and below opal glass were painted with optical white paint.)

Fig. 4
Fig. 4

Fractional change in reflectance vs fractional change in transmission for Nuclepore with the load away from the detector (solid stairs) and toward the detector (open stars) for benzene pyrolized soot.

Fig. 5
Fig. 5

Conceptual sketch of how the coverage factor F may take different values for the same mean surface density of absorbers (black dots) depending on physical characteristics: (a) fine particles, high absorbers with little or no aggregation and good surface contact (high F likely); (b) fine particles, high absorbers with considerable aggregation and poor surface contact (medium to low F likely); (c) external mixture–fine-particle absorbers mixed with coarse high-backscatter particles. [The F value depends on the relative proportion of the surface covered by each component (could be positive, zero, or negative)]; (d) internal mixture–fine-particle absorbers in nonabsorbing matrix (F values uncertain).

Fig. 6
Fig. 6

Figurative representation of the effect of absorbing and scattering particles on effecting Nuclepore internal reflectivity (see text).

Fig. 7
Fig. 7

(a) Results for laboratory-generated fine-pyrolized benzene soot (F = 0.9); (b) results for Seattle highway tunnel samples (F = 0.65); (c) results for CSU agglomerated propane flame soot (F = 0.35). A (—) modeled value of (ΔI/I0 NDS)/(ΔI/I0 opal) with measured values (○); B (★) modeled value for ratio of specified ideal ΔI/I0 to (ΔI/I0 NDS); C (○) modeled value for ratio of specified ideal ΔI/I0 to (ΔI/I0 opal); D (—) modeled values of diffuse ΔR/R0 with loaded surface facing detector and measured values (★); E (- - -) modeled values of diffuse ΔR/R0 with loaded surface away from detector and measured values (□). Model parameters: RS (opal) = 0.69; RS (NDS) = 0.12; R1 = 0.15; R2 = 0.5.

Fig. 8
Fig. 8

Scanning electron micrographs for various filter loads discussed in text. Magnification ~16,000×. (a) Fine-pyrolized benzene soot—Fig. 8 samples [example of Fig. 7(a) morphology]; (b) highway tunnel ambient—Fig. 9 samples [example of Fig. 7(c) morphology]; (c) CSU propane flame soot—Fig. 10 samples [example of Fig. 7(b) morphology]; (d) University of Washington ambient—Fig. 13 samples (particles in holes).

Fig. 9
Fig. 9

Same as Fig. 2 for coarse C, fine F, and total T fractions of random ambient aerosol samples. Numeral suffixes identify concurrent samples.

Fig. 10
Fig. 10

(a) Scanning electron micrograph of torn Nuclepore cross section showing top and bottom surfaces and particles in holes for University of Washington ambient aerosol (see Fig. 11). Magnification = 8000×. (b) Same as (a) with magnification = 15,500×.

Fig. 11
Fig. 11

Fractional change in reflectance vs fractional change in transmission for Nuclepore with load away from detector (□) and toward detector (★) for University of Washington ambient samples.

Equations (15)

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T 0 = I 0 ( 1 - R 1 ) T n T 3 ( 1 + T n 2 R 2 R 3 + T n 4 R 2 2 R 3 2 ) ,
T 0 = I 0 ( 1 - R 1 ) T n T 3 1 - T n 2 R 2 R 3 .
R b = I 0 R 1 + I 0 ( 1 - R 1 ) T n 2 T 2 R 2 R 3 ( 1 + T n 2 R 3 R 2 + T n 4 R 3 2 R 2 2 ) ,
R b = I 0 R 1 + I 0 ( 1 - R 1 ) T n 2 T 2 R 3 ( 1 + T n 2 R 3 R 2 + T n 4 R 3 2 R 2 2 ) .
T 0 = ( 1 - R 1 ) T n T 2 1 - T n 2 R 2 R 3 ,
R b = R 1 + ( 1 - R 1 ) T n 2 R 2 R 3 ( 1 - T n 2 R 2 R 3 ) .
T s = R b R s T 0 + R b 2 R s 2 T 0 + R b 3 R s 3 T 0
T s = R b R s T 0 1 - R b R s .
T = T 0 + T s = T 0 ( 1 + R b R s 1 - R b R s )
T = T 0 / ( 1 - R b R s ) .
R 3 ( L ) = R 2 ( 1 - F · L ) ,
T 2 = T 3 = ( 1 - R 2 ) .
R f = R 1 + ( 1 - R 1 ) T n 2 R 2 T 2 1 - T n 2 R 2 R 3 .
R f ( L ) = ( 1 - L ) 2 [ R 1 + ( 1 - R 1 ) T n 2 R 2 T 2 / ( 1 - T n 2 R 2 R 3 ) ] ,
R b = ( 1 - T x T y ) / [ R y = R x ( T x T y ) ] .

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